At the current state of the art in technology, multimedia processing is starting to become ubiquitous, and smart multimodal data capture and processing systems are at the edge of becoming universally used by individuals in their households. While large advances have been made in video processing, the audio counterpart is comparatively underdeveloped. The main reason for that is that the untethered (distant) acquisition of high-quality audio signals (e.g., of a human speech) requires a microphone array—a number of spatially separated microphones whose signals are processed in a way as to enhance the desired audio input and to suppress the undesired audio input.
Multichannel signal processing and microphone array research have very rich history. See, for example. M. Brandstein and D. Ward, eds. (2001). “Microphone Arrays: Signal Processing Techniques and Applications”, Springer-Verlag, Berlin, Germany. A common task in setting up a micro-phone array is to physically and electronically connect all microphones to the digitization hardware and further to the processing unit. Typically, a separate amplifier is used for each microphone, and each amplifier's output is fed to a separate channel of a analog-to-digital conversion (ADC) board. Such an architecture is heavily parallel, with one individual cable per microphone and all cables converging at a central hub. When the number of microphones becomes large, the amount of wiring involved makes the resulting system quite cumbersome.
A microphone array may comprise a number of individual microphones that are connected to a central processing unit. The microphones may each record their own independent audio signals and may be engaged in communication with one another and with the central processing unit for the purposes of recording synchronization and data transfer. Conventional microphone array configurations may have separate individual connections from the central processor to every microphone in the array, which may severely limit the flexibility and scalability of the microphone array system. Additionally, the digitization of the signal may occur only at the central processing unit, leaving the analog signals susceptible to noise and signal degradation over the signal transfer path. Further, a single analog-to-digital converter chip with multiplexed input may be used to perform analog-to-digital conversion for several microphones in the array, resulting in a non-simultaneous sampling on individual channels and ultimately in degradation of system's performance.
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